ok, so spent the last few days, hours on end, trying to figure out why it's taking forever and a day to transfer @1TB of data from a public drive currently residing on a physical HP server, win2008r2, to a recently fired up virtual windows 2012 r2 file server.

Without going into specifics on both physical box and the esxi host, let's assume hardware is not the problem because from a drive perspective, cpu, ram, etc...there is no way either is the bottleneck. we are talking excessive amounts of un-utilized ram, cpu power, 15k sas drives/RAID 1+﻿0, etc... Also, it's a Gigabit network across the board.

I have literally tried EVERYTHING reputable online (e.g. nic drivers, settings) and nothing works. Every time the transfer starts off blazing fast (maybe 80-90MB/sec and slows to a crawl under 10mb/Sec. To be sure it wasn't an esxi issue I even tried similar tranfers to other physical boxes (windows 2008+﻿) and same thing.

I find it baffling one can spend all this money on physical hardware, be it building out physical servers or esxi hosts with 15k sas drives, 48gb ram, 2 CPU's w/16 cores, etc...only to have F'in Windows kill a file transfer down to a crawl. performance otherwise (e.g. day to day drive access, applications, etc is fine - it's just copying large files).

Even tried different utilities (e.g. Teracopy, Robocopy, FTP, etc...) across the board virtually same thing.

Makes no dam sense so I hope I an really missing the obvious here and someone will come in and tell me I'm an idiot - here's the fix lol

I always suspect Antivirus first for this stuff. Turn off real-time protection on both sides (client and server) and try to rule our Antivirus issues. You'll know quickly, won't have to be off for long.

@7Tigers - tried all different methods to move the data - drag and drop, copy/past, ftp, 3rd party tools, and yes it's between shares on network. I don't think it's an overloaded switch cuz we are talking a 20 PC office during off-hours when no one was even there :-)

as for the SAN - Problem again, small office, small client - dollar is better spent on internal storage on the esxi host where we have 4TB of space - it's not in their budget to get the kind of $AN needed to match that performance they're getting with local storage on the esxi host. I have no doubts it will perform fine once i get the data over there - my beef is why is it taking so dam long lol-

The slowdown occurs like clockwork - from 80/90mb/sec down but does not correlate with any bottlenecks on the network side based on some basic permon observations done in simultaneously with the copy.

Another key factor which rules out network issues IMO - the storage craft backup, run from this SAME physical server, a complete image of that drive (FULL BACKUP), 942gb - completed in 5 hours and 16min. started 1am, finished 6:16am. Backups run very fast every night but those go to a NAS device.

10 MB/Sec sounds like 100 Mbps speed approximately in theoretical speed. Might be a duplexing issue between client and switch.

Set your NIC on client to 1000 Mbps full duplex. See if the Full Duplex light is lit on switch on your server port and client port. See if forcing it to 1000 Mbps helps.

Nope! Set your NIC's at HALF-DUPLEX for greater one-way speeds. This is likely the problem.Generally, full-duplex is used for general networking. Half-duplex is used for data backup systems (nightly backups). and one-way copying such as what the OP is doing.

[EDIT]: You could also isolate the two systems with a cross-over cable, since this is a "quiet" system (nighttime, no users). This will bypass your infrastructure.

[More EDITS]: Since this is a full TB of data, you could copy it to a USB 3.0 external drive @ 5x faster than your network speed, then upload it to the destination server very quickly, even with many small files. This also creates a data backup. :)

10 MB/Sec sounds like 100 Mbps speed approximately in theoretical speed. Might be a duplexing issue between client and switch.

Set your NIC on client to 1000 Mbps full duplex. See if the Full Duplex light is lit on switch on your server port and client port. See if forcing it to 1000 Mbps helps.

Nope! Set your NIC's at HALF-DUPLEX for greater one-way speeds. This is likely the problem.Generally, full-duplex is used for general networking. Half-duplex is used for data backup systems (nightly backups). and one-way copying such as what the OP is doing.

[EDIT]: You could also isolate the two systems with a cross-over cable, since this is a "quiet" system (nighttime, no users). This will bypass your infrastructure.

[More EDITS]: Since this is a full TB of data, you could copy it to a USB 3.0 external drive @ 5x faster than your network speed, then upload it to the destination server very quickly, even with many small files. This also creates a data backup. :)

10 MB/Sec sounds like 100 Mbps speed approximately in theoretical speed. Might be a duplexing issue between client and switch.

Set your NIC on client to 1000 Mbps full duplex. See if the Full Duplex light is lit on switch on your server port and client port. See if forcing it to 1000 Mbps helps.

Nope! Set your NIC's at HALF-DUPLEX for greater one-way speeds. This is likely the problem.Generally, full-duplex is used for general networking. Half-duplex is used for data backup systems (nightly backups). and one-way copying such as what the OP is doing.

[EDIT]: You could also isolate the two systems with a cross-over cable, since this is a "quiet" system (nighttime, no users). This will bypass your infrastructure.

[More EDITS]: Since this is a full TB of data, you could copy it to a USB 3.0 external drive @ 5x faster than your network speed, then upload it to the destination server very quickly, even with many small files. This also creates a data backup. :)

He's not talking about backups being slow.

Please fully read my complete comment above. It is accurate. The OP is doing a large one-way copy, similar to one-way backups. In particular, note my comment: "... and one-way copying such as what the OP is doing...."

@Aaron - ok so as a relative esxi noob - do i turn off TCP Offload somewhere on the esxi host or is that done within the Windows guest? (using vmxnet3) as virtual adapter. For the physical machines I obviously do it on the cards themselves - that I know

10 MB/Sec sounds like 100 Mbps speed approximately in theoretical speed. Might be a duplexing issue between client and switch.

Set your NIC on client to 1000 Mbps full duplex. See if the Full Duplex light is lit on switch on your server port and client port. See if forcing it to 1000 Mbps helps.

Nope! Set your NIC's at HALF-DUPLEX for greater one-way speeds. This is likely the problem.Generally, full-duplex is used for general networking. Half-duplex is used for data backup systems (nightly backups). and one-way copying such as what the OP is doing.

[EDIT]: You could also isolate the two systems with a cross-over cable, since this is a "quiet" system (nighttime, no users). This will bypass your infrastructure.

[More EDITS]: Since this is a full TB of data, you could copy it to a USB 3.0 external drive @ 5x faster than your network speed, then upload it to the destination server very quickly, even with many small files. This also creates a data backup. :)

He's not talking about backups being slow.

Please fully read my complete comment above. It is accurate. The OP is doing a large one-way copy, similar to one-way backups. In particular, note my comment: "... and one-way copying such as what the OP is doing...."

No. He's not. He said, "Unfortunately we are talking a lot of smaller files - ton of files as opposed to a few larger files."﻿

This person is a verified professional.

So are the file transfers only slow from client to server and which server are the transfers slow to? What is the speed like from workstation to workstation or between servers? Server 2012 has a feature called digital signing that you may want to try and disable.

Could be the cache filling up on the RAID cards and then you're down to actual write speeds. With tons of small files you are simply maxing out the ability of the system in terms of file speed not data speed. This is one of the key differences between low/mid range RAID cards and high end cards.

The easy test is what has already been suggested. Offload the files to a portable drive of some sort, preferably a fast USB 3.0 drive. Then upload them onto the destination system and see what happens.